Final answer:
To make the reversing valve slide move, the system must have a pressure difference between the two sides of the valve.
Step-by-step explanation:
In a hydraulic system with a reversing valve slide, the movement of the slide is caused by a pressure difference within the system. To make the reversing valve slide move, there must be a pressure difference between the two sides of the valve. This pressure difference is necessary to overcome the friction and resistance of the valve and allow the slide to move.
For example, if one side of the valve has a higher pressure, say P₁, and the other side has a lower pressure, say P₂, then the pressure difference is P₁ - P₂. This pressure difference creates a net force on the slide, allowing it to move.
So, to make the reversing valve slide move, the system must have a pressure difference.